In recent years, the applications of digital imaging technologies have flourished. As the costs of computation continue to decline and the sophistication of imaging programs increases, more applications of imaging technology become apparent. These applications range from the relatively mundane, such as document imaging, to the relatively esoteric, such as virtual reality imaging. It is becoming apparent that the market potential of computerized imaging techniques has only begun to be realized.
Among the many existing and potential applications of imaging technologies is the digitized imaging of photographs, paintings, and the like, and facsimiles thereof. Once such images are obtained in digitized form, either by conversion of an analog original or by direct production, as with a computer-aided design (CAD) system, they can be manipulated in a virtually unlimited number of ways. For example, the images can be enhanced with respect to color, contrast or size, "cut and pasted" onto a different image, and formatted on a timeline to produce a motion picture.
A typical imaging system comprises a computer having adequate storage capacity to record the image to be processed, an image production device, such as a scanner, to digitize the original image, an image processor, which is designed to speed up the available image manipulations, and an output device where the processed image is received. Although each of the above-mentioned components of a typical imaging system continues to evolve as the technology advances, the final stage of image processing, namely, the transfer of a processed image onto a desired medium, is of particular interest herein.
The relatively low cost and convenient use of ink-jet printers make such printers the generally preferred devices for recording processed images. Unfortunately, the acceptability of the recorded images produced with ink-jet printers is in many cases highly dependent on the recording medium. Conventionally, the recording medium used with an ink-jet printer is paper, which is provided as a plain-type or coated-type paper. However, for many applications, such as for the imaging of portraits, paper is not a suitable recording medium. Other recording media that would preferably be used under many circumstances include artist's canvas, textiles, leather, and durable plastic sheets.
Key among the concerns in using any recording medium are the extent to which the medium permits "print through" of ink and the extent to which the medium resists ink absorption. In the case of "print through," the ink penetrates through the medium and can readily be perceived from the opposing side. This is particularly problematic when large amounts of ink are employed, as in full-color printing. On the other hand, whenever the print medium resists ink absorption, blotting or feathering of ink on the surface can occur since the ink is not sufficiently absorbed into the medium.
Frequently, a sizing agent, which fills the pores of the recording medium, is employed in an effort to give the medium the desired balance of ink absorptivity and penetration resistance, especially when the medium would otherwise have excessive ink penetration. For example, U.S. Pat. Nos. 5,279,885 and 4,785,461 propose recording sheets for use with ink-jet printers comprising fibrous base material and several sizing agents. However, it is often found that sizing agents tend to migrate over time in the recording medium, thereby causing changes in the ink absorptivity of the medium and reducing overall print quality of the recorded image.
In other cases, the desired recording medium resists ink penetration excessively, such as with nonporous or coated porous substrates. An example of the latter kind of substrate is that of porous corrugated packages coated with clay-based or other coatings, which coatings improve the flexographic printing properties of the packages. An approach to rectifying the poor ink absorptivity for ink-jet printing of these packages has been proposed (see, e.g., Larson, M., Packaging, pp.49, (December 1991)), which involves reformulating the water-based inks to include acrylic-based or alcohol-based formulations. However, reformulating the inks likely would require making adjustments to printheads and other machine components.
The printing of nonporous substrates with an ink-jet printer has received generally less study than the printing of porous substrates. For example, a recording material comprising a nonporous base material and a surface recording layer formed thereon has been proposed (U.S. Pat. No. 4,680,235). The surface recording layer reportedly is formed at least with a surface active agent that does not form an insoluble material in the ink, and optionally, is formed with a binder agent which is soluble in or swells in an aqueous ink. The charge of the surface active agent, e.g., cationic, anionic or neutral, in the surface recording layer apparently must be matched with the charge of the dye present in the ink composition. Few nonporous substrates are shown to be ink-jet printable with this approach.
Although much effort has been expended on adapting paper and paper-like media for use with high speed printers, such as full-color ink-jet printers, little success is noted for adapting non-paper media for use with such printers. It is believed that this is not due so much to an unrecognized market for such applications as much as to the continued failure of those in the field to develop such materials or possibly the widespread belief that such applications are not possible. Accordingly, it is desired to provide novel recording media that can be used with ink-jet printers, which high ink absorptivity yet show acceptably low "print-through" characteristics. In particular, it is desired to provide novel recording media prepared from such substrates as canvas, textiles, and polymeric sheets and films. Such recording media are expected to offer qualities, such as improved aesthetics, durability, and the like, which are not attainable with conventional paper and other fibrous materials.